Add HeyOnCall MCP Server (#2559)

Co-authored-by: adam jones <domdomegg+git@gmail.com>

Author: compumike

README.md

@@ -214,6 +214,7 @@ Official integrations are maintained by companies building production ready MCP
 - <img height="12" width="12" src="https://gyazo.com/favicon.ico" alt="Gyazo Logo" /> **[Gyazo](https://github.com/nota/gyazo-mcp-server)** - Search, fetch, upload, and interact with Gyazo images, including metadata and OCR data.
 - <img height="12" width="12" src="https://cdn.prod.website-files.com/6374050260446c42f94dc90f/63d828be3e13d32ee6973f35_favicon-32x32.png" alt="Harper Logo" /> **[Harper](https://github.com/HarperDB/mcp-server)** - An MCP server providing an interface for MCP clients to access data within [Harper](https://www.harpersystems.dev/).
 - <img height="12" width="12" src="https://www.herokucdn.com/favicons/favicon.ico" alt="Heroku Logo" /> **[Heroku](https://github.com/heroku/heroku-mcp-server)** - Interact with the Heroku Platform through LLM-driven tools for managing apps, add-ons, dynos, databases, and more.
+- <img height="12" width="12" src="https://heyoncall.com/favicon.ico" alt="HeyOnCall Logo" /> **[HeyOnCall](https://heyoncall.com/blog/mcp-server-for-paging-a-human)** - Page a human, sending critical or non-critical alerts to the free [HeyOnCall](https://heyoncall.com/) iOS or Android apps.
 - <img height="12" width="12" src="https://www.hiveflow.ai/favicon.ico" alt="Hiveflow Logo" /> **[Hiveflow](https://github.com/hiveflowai/hiveflow-mcp-server)** - Create, manage, and execute agentic AI workflows directly from your assistant.
 - <img height="12" width="12" src="https://img.alicdn.com/imgextra/i3/O1CN01d9qrry1i6lTNa2BRa_!!6000000004364-2-tps-218-200.png" alt="Hologres Logo" /> **[Hologres](https://github.com/aliyun/alibabacloud-hologres-mcp-server)** - Connect to a [Hologres](https://www.alibabacloud.com/en/product/hologres) instance, get table metadata, query and analyze data.
 - <img height="12" width="12" src="https://brew.sh/assets/img/favicon.ico" alt="Homebrew Logo" /> **[Homebrew](https://docs.brew.sh/MCP-Server)** Allows [Homebrew](https://brew.sh) users to run Homebrew commands locally.